1. Field of the Invention
The present invention relates to an implant such as an implant embedded in bones and a dentistry implant and a method of manufacturing the same, and more particularly to an implant with bioactive particles stuck and a method of manufacturing the same.
2. Description of the Related Art
Titanium or titanium alloy is generally used as material of implants such as an implant embedded in bone and a dentistry implant at present. This is because when the implant is installed, the material of the implants has a state called "osteo-integration" in which the implant directly contacts bone. The osteo-integration implies the state in which there is no connective tissue between the bone and the implant. If other material is used, there is a case that the osteo-integration is not realized and a fibrous connective tissue is intervened between the implant and the bone. For this reason, the whole implant is finally covered by the fibrous connective tissue so that the fluctuation of the implant starts. Therefore, the implant must be pulled out.
In order to further increase the effect of the osteo-integration, it could be considered that the surface of the implant is made rough. There could be various methods of making the implant surface rough. For instance, as one of the methods, there is a method in which beads of metal titanium are sprayed in plasma such that the surface of the implant has many hemispheric titanium (Ti) protrusions in a microscope level and the surface area of the implant is increased. This technique also makes it possible to increase the bio-compatibility of the implant with bone cells. Another method is a sand blasting method using grinding particles of alumina and so on. In this method, the surface area of the implant is increased to reflect the size of the grinding particles. Also, an anchor effect is achieved because bone enters into concave portions of the implant.
Also, the implant that a hydroxylapatite (HAP) layer is coated on the surface of the implant of titanium is commercially available. In such an implant, the connection state between the bone and the hydroxylapatite layer is called bio-integration, and it is said that the implant and the bone are chemically coupled to each other. The bio-integration is stronger than the osteo-integration in coupling strength. In a method of coating the hydroxylapatite layer, a powder of hydroxylapatite is adhered to the surface of the implant by a plasma thermal spraying method and so on. Because the hydroxylapatite layer of the implant is an aggregation of powder, the surface of the implant has portions with very small unevenness and has the above-mentioned anchor effect.
However, there are the following problems in the above-mentioned conventional implants. In the implant having the surface where the beads of titanium are sprayed in the plasma, because the plasma spraying method is the very advanced technique which requires high cost, the final implant cost becomes very expensive. On the other hand, it is possible to manufacture with low cost the implant having the surface which is subjected to the sand blasting process using the alumina grinding particles. However, there is a problem in that it is difficult to remove the adherent alumina grinding particles so that bioinert alumina particles are remained on the surface of the implant. Therefore, the formation of osteo-integration is prevented.
Further, it is in the present situation that there is little implant that the hydroxylapatite layer is coated as the commercially available products. The reason is that advanced technique is needed in the hydroxylapatite coating and it is costly. Also, the reason is that the implant having a titanium surface is finally superior to the implant having the hydroxylapatite layer, because bone coupling state is destructed through delamination of the hydroxylapatite coating layer.